r - ggplot条形图中的水平白线

Question

当我使用 ggplot2 和 geom_col() 从 R 保存图形时或 geom_bar(stat = 'identity')它出现了一些难看的水平白线。
数据如下所示:

> head(mouse_track_data)
session site BM.pile ox.pile       type  mice skinks geckos 
1 dec_2018    1       1    1.10 control FALSE   TRUE  FALSE            
2 dec_2018    1       2    1.12 design1 FALSE  FALSE  FALSE           
3 dec_2018    1       3    1.11 control FALSE  FALSE  FALSE            
4 dec_2018    1       4    1.80 control FALSE  FALSE  FALSE            
5 dec_2018    1       5    1.60 design1 FALSE  FALSE  FALSE            
6 dec_2018    1       6    1.50 control FALSE  FALSE  FALSE            

这是我的代码:

ggplot(data = mouse_track_data, aes(x = session, y = as.numeric(mice), fill = type)) + 
  geom_bar(stat='identity') +
  theme_classic() +
  theme(text = element_text(size=15),
        axis.text.x = element_text(angle = 45, hjust = 1)) +
  xlab("Tracking session") +
  ylab("Number of tunnels with mouse tracks") +
  theme(axis.title.y = element_text(margin = margin(t = 0, r = 7, b = 0, l = 0))) +
  theme(axis.title.y = element_text(margin = margin(t = 0, r = 7, b = 0, l = 0)))  +
  theme(legend.title = element_blank(), legend.position = c(-2, -2)) +
  scale_fill_manual(values = c("control" = "#37a1c1", "design1" = "#9ce2cb", "design2" = "#445a9c"),
                    labels = c(" Control", " Single grade", " Mixed grade")) +
  scale_x_discrete(labels = c('Dec 2019', "April 2019", "Nov 2019", "March 2020")) +
  scale_y_continuous(breaks=seq(0, 50, 10), limits = c(0,52), expand = c(0,0)) +
  theme(axis.line = element_blank())

有了这个，或使用 geom_col() , 导出为 ESP 或 PDF 时，我得到一个如下所示的图:

细白线穿过所有列。我认为这与它计算每个数据点然后堆积它们有关？
如果我用 geom_bar() 做代码它没有白线，但它没有显示我想要的数据。

Answer 1

当您使用 geom_col()您将获得每个数据值的一个条形段，这会创建您的白线。以下示例以夸张的方式显示了这一点。

library(tidyverse)

mtcars %>%
  mutate(cyl = factor(cyl), am = factor(am)) %>%
  ggplot(aes(x = cyl, y = 1, fill = am)) +
  geom_col(color = "white")

最简单的解决方法是手动聚合，例如与 group_by()和 summarize() :

mtcars %>%
  mutate(cyl = factor(cyl), am = factor(am)) %>%
  group_by(cyl, am) %>%
  summarize(count = n()) %>%
  ggplot(aes(x = cyl, y = count, fill = am)) +
  geom_col(color = "white")
#> `summarise()` regrouping output by 'cyl' (override with `.groups` argument)

创建于 2020-09-26 由 reprex package (v0.3.0)
注: geom_col()与 geom_bar(stat = "identity") 相同.